Ultrasonic cleaning processes typically use metal tanks that contain a liquid and parts to be cleaned. Ultrasonic energy is supplied to the tank by ultrasonic transducers, which may be attached to or immersed in the tank. The walls and floor of the tank are typically 0.25 inch or 8 gauge or 10 gauge stainless steel. The walls and floor of the tank absorb some of the ultrasonic energy produced by the ultrasonic transducers, which decreases the amount of ultrasonic energy that can be employed in the cleaning processes.
It is known that ultrasonic vibrations used to excite liquids bounce off metal if there is air on the other side of the metal and the metal is relatively thin. For example with air on the other side of 14 gauge steel, ultrasonic activity has been measured to bounce off nine times more effectively than with 0.25 inch steel. The ultrasonic vibrations are reflected rather than absorbed by a thin metal panel backed with air. However, it is not practical to fabricate tanks out of 14 gauge metal because relatively thicker materials are needed for structural integrity and durability.